Accelerating Electron-Transfer Dynamics by TiO 2 -Immobilized Reversible Single-Atom Copper for Enhanced Artificial Photosynthesis of Urea.

Photocatalysis as a sustainable technology is expected to provide a novel sight for the green synthesis of urea directly using N 2 , CO 2 , and H 2 O under mild conditions. However, the fundamental issue of inefficient electron transfer in photocatalysis strongly hinders its feasibility, especially for the above multi-electron-demanding urea synthesis. Herein, an effective strategy of accelerating electron-transfer dynamics is reported by TiO 2 -immobilized reversible single-atom copper (denoted as Cu SA-TiO 2 ) to enhance the performance for photosynthesis of urea from N 2 , CO 2 , and H 2 O. As revealed by a series of quasi-in-situ characterizations (e.g., electron paramagnetic resonance, and wavelength-resolved and femtosecond time-resolved spectroscopies), the expedited dynamics behaviors originating from reversible single-atom copper in as-designed Cu SA-TiO 2 (electron extraction rate: over 30 times faster than the reference photocatalysts) allow the assurance of abundant and continual photogenerated electrons for multi-electron-demanding co-photoactivation of N 2 and CO 2 , resulting in considerable rates of urea production. The strategy above for improving the photoelectron-extraction ability of photocatalysts will offer a high-efficiency and promising route for artificial urea photosynthesis and other multi-electron-demanding photocatalytic reactions.